I’m not sure how quickly they figured this out, but figure it out they did; notations from the City of Davis website says (retrieved 1/19/2017. Emphasis added):

Sycamore Lane Experiment: This 1967 bike lane used concrete bumpers to separate parked cars from the bike only lane. The parked cars screened the visibility of bicyclists coming into intersections and cars would unknowingly drive into the bike lane. This bike lane design was eventually abandoned.
The 1967 separated bike lanes on Sycamore Lane didn’t prevent conflicts with turning vehicles. Today at this intersection there are special bike-only traffic signals that provide cyclists their own crossing phase. These innovative bicycle signals were the first of their kind to be installed in the United States.